Table roll



June 25, 1963 J. D. ROBERTSON TABLE ROLL Filed June 12, 1961 FIG. I

FIG. 2

FIG.3

INVENTOR. JOHN D. ROBERTSON fi y, 04%

ATTORNEYS 3,094,769 TABLE ROLL John D. Robertson, Taunton, Mass,assignor to Mount Hope Machinery Company, Taunton, Mass, a corporationof Massachusetts Filed June 12, 1961, Ser. No. 116,576 7 Claims. ((31.29116) This invention relates to rolls for supporting traveling webs,and more particularly concerns a new and improved table roll whichmaintains an axially straight configuration in use, although the rollmay be of relatively great length and small diameter.

The roll of this invention is particularly adapted for use inpaper-making machines, although it has utility in many otherapplications. In the manufacture of sheet paper, the present practiceinvolves depositing a thin suspension of fibre in water on a fine meshscreen, commonly referred to as a wire, which is moving in a horizontalpath at high speed and supported by a number of table rolls arrangedtransversely below the web. The water in the suspension is allowed todrain through the wire to leave a layer of pulp on the wire surface. Thepulpy layer is subsequently pressed and dried into sheet paper and woundonto a roll.

During the initial stages in the formation of the paper sheet, it isimportant that the wire be maintained in as flat a condition aspossible. Should the wire sag along its center, the watery suspensionwould tend to drain towards the center-line with the result that thefinished paper sheet would be thicker at its center than at its edges.In order for the wire to present a fiat surface, it follows that thesupporting table rolls must be axially straight throughout their entirelength.

Heretofore, some of these rolls, which run up to 20 feet or more inlength, have been made slightly barrel-shaped to compensate for the sagso that, when mounted horizontally, the upper screen-supporting portionwill be longitudinally straight. This type of table roll is quiteexpensive to produce and has not given entirely satisfactoryperformance. Other table rolls have been made quite strong and with arelatively large diameter ('16 inches for example) in order to support,without sagging, the weight or the Wire and the partly formed paper.While this measure is effective in providing a generally straight roll,the resulting increase in roll diameter adversely affects the drainingof water through the wire. It has been found that when table rolls ofrelatively large diameter are used to support the wire, a fillet ofwater tends to build up beneath the wire along the upper quadrant on thedischarge side of the roll. This fillet of water creates a rather highvacuum (up to 26 inches) which pulls the wire down and slightly aroundthe roll. From time to time, the fillet will burst, breaking the vacuumso that the wire snaps up. When this occurs, the wet pulp will fly ofithe wire, spot ting the adjacent area and generally disrupting thesheetforming process. However, a table roll of relatively small outsidediameter eliminates this problem and has the further advantage ofpermitting a greater number of rolls to be used in supporting the wirewithout creating an objectionable vacuum. But, for reasons alreadystated, any such small-diameter roll must be axially straight when inoperation.

Accordingly, it is an object of the present invention to provide a tableroll which, in its normal use, will be axially straight although ofrelatively great length and small diameter.

Another object of this invention is to provide an improvedaxially-straight table roll which is of simple, lowcost construction,yet completely dependable in operation.

More particularly, the roll of this invention comprises United StatesPatent 3,094,769 Patented June 25, 1963 a stationary axle and an outersleeve rotatably mounted thereon. During the course of its manufacture,the axle is bowed with a longitudinal curvature lying in a single planeof a predetermined camber. The term camber refers to the maximum lateraloffset of the longitudinal centerline of the axle from the rectilinearaxis joining the centerline at the ends of the axle. Following assemblyof the sleeve on the axle, the curved roll is stationarily mounted in anupwardly convex position, with the plane of curvature of the axisextending vertically through the rectilinear axis. The camber of theaxle is of a pre-selected value sufilcient to compensate for its ownweight and that of a load which the roll is intended to carry, so thatthe elastic deflection produced by these loads Will cause the axle andthe roll to assume the desired axiallystraight condition. In the moregeneral case, in which the roll is subjected to a resultant force vectoracting trans- Vcrsely thereon, but not necessarily vertically, the axleis oriented so that the resultant lies in the plane of curvature, andacts oppositely to the direction of camber of the axle.

These and other features of the invention, along with further objectsand advantages thereof, will be more readily apparent from the followingdetailed description of a preferred embodiment thereof, taken inconnection with the accompanying drawings, in which:

FIG. 1 is a view in side elevation of an unmounted table roll madeaccording to this invention;

FIG. 2 is a similar view, showing the roll mounted in operating positionand under a normal load; and

FIG. 3 is a fragmentary sectional view in side elevation, showingcertain details of construction of the roll.

Referring to :FIG. 1, there is illustrated an unmounted and unloadedtable roll 10 having a longitudinally curved tubular axle 12 having acamber C.

The degree of curvature for a particular roll axle may be variedaccording to the conditions under which it is designed to operate, butthe camber should be equal to the elastic deflection which will beproduced at the iongitudinal center of the axle by the weight of thecomplete roll and that of the intended load. This value may be readilycalculated in a well-known manner for particular forms and dimensions ofaxles, and load weights.

Referring to FIG. 3, a slightly resilient, hard corrosionresistantsurface sleeve 14 is disposed lengthwise about the axle and supportedfor rotation thereon by a number of 'spool assemblies 16 arranged inaxially-spaced relation. Each spool assembly comprises a ball bearingunit 18, an annular spacing element 20 for axially spacing the bearingunits, and an annular roll sleeve 22 mounted upon the outer race of eachball bearing to support the surface sleeve 14. Locking rings 24 havingset screws 25 are mounted at oppote ends of the axle to maintain theseveral parts in assembled relation.

Since the roll will normally be in use where a great deal of water ispresent, it is desirable that the ends of the sleeve 14 be closed byannular plates 26, and that the ends of the tubular axle be sealed byabutrnents 28. In conjunction with the plates 26, any well-known form ofrotatable fluid seal may also be used if desired.

As shown in FIGS. 2 and 3, the roll is mounted in a horizontal plane bymeans of brackets 32 receiving opposite ends of the axle 12 to mountthem upon suitable fixed supports 34. To prevent the axle from turningabout its longitudinal axis, keys 35 are received in keyways 36 formedin the brackets 32, and in a keyway 37 which may be formedlongitudinally the full length of the axle as shown, or limited to theend portions of the axle. One or more set screws 38 are threaded into atleast one of the brackets 32 to axially secure the axle therein. It willbe apparent that other locking arrangecording to several fiactors.sleeve, their-configurations, diameters and moduli of elasments may beprovided to hold the axle in the desired position.

The roll is mounted in an upwardly convex position, with the plane ofcurvature of the axle cxtendin g vertically through the rectilineanaxisdetermined by the ends of the roll. "In FIGS. 2 and .3, :the roll isshown deflected to an axially straight configuration under thegravitational forces of "the rolls own weight and the predeterminedweight of a fine mesh screen .or wire 39 carrying. a layer of pulp 40over the top of the roll .in normal operation. All of the major forces:acting to deflect the roll are directed vertically downward and,accordingly, the vertical orientation of the .plane of curvature of the.axle results in an elastic deflection balancing the load in anaxiallystraight condition of the roll. Obviously, the roll axle maybeset at any angular degree to compensate for known ad1vectors which arenot vertical. For example, in a conveyor system, the first and lastrolls will be subjected to the vertical force of gravity plus thehorizontal component of the tension of the conveyor belt. Under suchcircumstances, the roll axle would be set so that the convex side of the.roll will be oriented in the plane of the vectorial resultant of thetwo force components.

The degree of set longitudinal curvature or camber that should beintroduced into the roll axle will vary ac- The length of the axle andticity, as well as the weight of the roll and the intended opera-tingload, must be considered in order to establish the proper degree ofcurvature, in accordance with wellknown theories of the deflection ofsimply-supported beams.

While the :roll axle has been illustrated-and described as tubular inshape, which is generally preferable by reason of its relatively highstrength and rigidity for a given weight, it will be understood that asolid axle .could be used if'desired.

A table roll made according to the invention has several advantages notpresent in table rolls heretofore available. This construction permitsthe fabrication of elongated, relatively small-diametert-able-rolls'which will not sagin use, but will be axiallyistraightunder the operating loads for which they are designed. For reasonsalready presented, rolls of relatively small diameter are highlydesirable in the manufacture of paper. sincethey contribute 'to'animproved-product.

While the invention has been described with particular reference to apreferred embodiment for purposes of illustration, it will be understoodthat various modifications may be made without departing from the truescope of the invention.

Having thus described my invention, what I claim and esire :to secureby.Letters Patent of the United States is: .1. A roll comprisingan'elongated axle and an annular sleeve, .means rotatably mounting andsupporting said sleeve against transverse sagging with respect to saidaxle,

thetaxlebeing a stiifi-beam permanently set in a bow with apredetermined longitudinal curvaturelying in a plane,

.means stat-ionarily supporting said axle horizontally for subjectiontoapredetermined resultant force acting transversely thereon, said axlebeing oriented with said resultant lying in said plane of curvature andacting against the convex side of the how, the degree of bow beingpreselected forelastic-deflection of said roll to a longitudinallystraight configuration by said resultant.

2.. A roll comprising an elongated axle and an annular sleeve, meansrotatably mounting and supporting said sleeve against transverse.sagging with respect to said axle, the axle being a still beampermanently set in a bow with a predetermined longitudinal curvaturelying in a plane, means stationarily supporting said axle horizontallyfor subjection to a predetermined weight, said axle being oriented withsaid plane extending vertically and said bow upwardly convex, the degreeof said how being preselected for elastic deflection of said roll to alongitudinally straight configuration by said weight.

3. A roll comprising an axle being a stiff beam longitudinally curved ina plane with a permanent set, and a sleeve, means rotatably mounting andsupporting said sleeve against transverse sagging with respect to saidaxle, the camber of the curvature of said axle having a valuepreselected to compensate for a predetermined force vector actingtransversely against said roll, said axle being supported substantiallyat its ends and oriented so that said force vector lies in said planeand acts oppositely to the direction of said camber, such that saidforce vector deflects said roll to .a longitudinally straight condition.

directed upwardly, such that said weight deflects said roll toalongitudinally straight condition.

.5. A .roll comprising an elongated axle, a plurality of :bearingsmounted on'said'ax-le in axially-spaced relation,

an annular sleeve rotatably mounted on said bearings, means supportingsaid sleeve against transverse sagging with respect to said axleintermediate said bearings, said axle being a still beam and :having aset longitudinal curv-ature lying in a plane, saidaxle being supportedsubstantially at its ends for subjection to a predetermined force vectortransverse thereto, said axle furtherbeing oriented so that said forcevector lies in said plane of curvature oppositely to the direction ofcurvature, the camber of said curvature being of a preselected valuesuch that said roll is elastically deflected by said force vector to alongitudinally straight configuration.

6. A table roll comprising an elongated axle being a still beamlongitudinally curved in a plane, an annular sleeve surrounding saidaxle, aplurality of bearings axially spaced on-said axle and rotatablysupporting said sleeve thereon, means supporting said sleeve againsttransverse sagging with respect to said axle intermediate said bearings,thecaniber of the curvatureof said axle being 'of a preselected value tocompensate for a predetermined rcsultant'of -forces acting transverselyagainst said roll,

said axle being supported substantially at its ends and so oriented thatsaid resultant lies in said-plane of curvature and is oppositelydirected to the camber of said axle,

such'that said resultant elastically deflects said roll into alongitudinally straight configuration.

7. -A roll comp-rising an elongated axle, a pluralityof spoolassemblies-each including at least one bearing and a spool-rotatablysupported by said bearing, said spool assemblies being mountedon saidaxle in axially-spaced relation, an annular sleeve rotatablymounted onthe spools of said spool assemblies, said spools supporting said sleeveagainst transverse sagging with respect to said axle-intermediate saidbearings, said axle beinga stitf beamand having a setilongitudinalcurvature lying in a plane, said axle-being supported substantially atits ends=for subjection to a. predetermined force vector transversethereto, said axle further being oriented so that said force vector'lies in said plane of curvature oppositely to the direction ofcurvature, the camber of said curvature being of-a preselected valuesuch that said roll is elastically deflected by 2,952,889 Hanssen Sept.20, 1960

1. A ROLL COMPRISING AN ELONGATED AXLE AND AN ANNULAR SLEEVE, MEANSROTATABLY MOUNTING AND SUPPORTING SAID SLEEVE AGAINST TRANSVERSE SAGGINGWITH RESPECT TO SAID AXLE, THE AXLE BEING A STIFF BEAM PERMANENTLY SETIN A BOW WITH A PREDETERMINED LONGITUDINAL CURVATURE LYING IN A PLANE,MEANS STATIONARILY SUPPORTING SAID AXLE HORIZONTALLY FOR SUBJECTION TO APREDETERMINED RESULTANT FORCE ACTING TRANSVERSELY THEREON, SAID AXLEBEING ORIENTED WITH SAID RESULTANT LYING IN SAID PLANE OF CURVATURE ANDACTING AGAINST THE CONVEX SIDE OF THE BOW, THE DEGREE OF BOW BEINGPRESELECTED FOR ELASTIC DEFLECTION OF SAID ROLL TO A LONGITUDINALLYSTRAIGHT CONFIGURATION BY SAID RESULTANT.